Depression and anxiety adversely affect millions of individuals, causing significant mortality and morbidity. Clinical studies over several decades suggest that these behavioral disorders emanate from both genetic factors and exposure to environmental factors. The interrelationships between genetic predisposition to these disorders, and how environmental and social factors modify genetic predisposition is critical to the development of clinical strategies for preventing these devastating disorders. For this purpose, we are using a monkey model to examine how social stress during early development triggers anxious and depressive behaviors and how social support modulates the development of these behaviors. Infant Japanese macaques are being tested early in life for temperament and growth hormone (GH) responsiveness. Clinical studies show a correlation between inhibited temperament and blunted GH responsiveness, and the anxiety and depressive disorders. Infant monkeys are then separated from their mothers and reared in a normal social colony environment. Behavioral studies are being used to determine if infants who receive greater social support have a decreased probability of developing anxious and depressive behaviors, compared to infants who receive less social support.